This is a type of exhaust system specifically designed for the BMW E9x M3. It has valves made from titanium and stainless steel, which allow for improved performance. The cat-back design helps to reduce back pressure on the engine, resulting in increased power and torque. Here's a sound clip https://www.instagram.com/reel/Ckgnp6oJHi0/?igshid=NjZiMGI4OTY%3D
Gains of 10-15 HP.